Fault protection with a digital computer

A fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation. Logic operations are given to detect a fault, locate it and initiate the opening of the appropriate circuit breakers, whether the fault is in the station or on lines radiating from the station. The instantaneous value of the station voltages and currents are sampled at a 0.5 ms rate, converted to digital form and stored for computer main-frame use. Operating times are compatible with the 25 ms breaker trip capability of modern two-cycle breakers. Computer speed in initiating tripping is a maximum of 4 ms for severe faults and a maximum of 10 ms for moderate or distant faults. Little attention has been given to hardware or programming aspects; instead this treatment represents the viewpoint of a protective-relay engineer who is attempting to answer the question: can it be done and what is involved? However, major emphasis was placed on minimizing computer main-frame duty

Interview with Jay Rockefeller by Brien Williams

Biographical Note John Davison “Jay” Rockefeller was born June 18, 1937, in New York to Blanchette Ferry (Hooker) and John D. Rockefeller III. He has served as a Democratic U.S. Senator representing West Virginia since 1985. Prior to that (1977-1985), he was governor of West Virginia. He is married to Sharon Percy, daughter of former Illinois Senator Charles “Chuck” Percy. He worked closely with Senator Mitchell on the 1993 health care reform package. Summary Interview includes discussion of: description of Senator Mitchell; differences in majority leader styles; Senator Byrd; story of President Clinton’s coming to the Democratic Caucus; their shared love of baseball and the Red Sox; the culture in the U.S. Senate and it has changed; Rockefeller’s switch from Republican to Democrat; health care debate in 1993 and Hillary Clinton; North American Free Trade Agreement (NAFTA); Mithchell’s U.S. Senate retirement; Mitchell’s legacy; Rockefeller’s transition from governor to senator; and reflections on the Kennedy family and politics

Metal Cooling in Simulations of Cosmic Structure Formation

The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars, where metal-free gas-clouds have been shown not to fragment. Adding metal cooling to numerical simulations has traditionally required a choice between speed and accuracy. We introduce a method that uses the sophisticated chemical network of the photoionization software, Cloudy, to include radiative cooling from a complete set of metals up to atomic number 30 (Zn) that can be used with large-scale three-dimensional hydrodynamic simulations. Our method is valid over an extremely large temperature range (10 K < T < 10^8 K), up to hydrogen number densities of 10^12 cm^-3. At this density, a sphere of 1 Msun has a radius of roughly 40 AU. We implement our method in the adaptive mesh refinement (AMR) hydrodynamic/N-body code, Enzo. Using cooling rates generated with this method, we study the physical conditions that led to the transition from Population III to Population II star formation. While C, O, Fe, and Si have been previously shown to make the strongest contribution to the cooling in low-metallicity gas, we find that up to 40% of the metal cooling comes from fine-structure emission by S, when solar abundance patterns are present. At metallicities, Z > 10^-4 Zsun, regions of density and temperature exist where gas is both thermally unstable and has a cooling time less than its dynamical time. We identify these doubly unstable regions as the most inducive to fragmentation. At high redshifts, the CMB inhibits efficient cooling at low temperatures and, thus, reduces the size of the doubly unstable regions, making fragmentation more difficult.Comment: 19 pages, 12 figures, significant revision, including new figure

Management of Banana Xanthomonas Wilt: Evidence from impact of adoption of cultural control practices in Uganda

Banana Xanthomonas Wilt (BXW) is an important emerging and non-curable infectious plant pathogen in sub-Saharan Africa that can cause up to 100% yield loss, negatively impacting sustainable access to food and income to more than 100 million banana farmers. This study disentangles adopters into partial and full adopters to investigate the factors that are relevant to sustain the adoption process of BXW control practices and quantifies the impact of adopting the practices. Data from a randomly selected sample of 1200 banana farmers in Uganda where the disease is endemic was used. A multinomial logit model was used to determine the factors affecting adoption of control practices and augmented inverse probability weighting was employed to estimate the impacts of adoption on banana productivity and sales. Results show that training a woman farmer and having diverse sources of information about BXW control practices increased adoption of the control practices and reduced the disease incidences. Farmers who adopted all the recommended control practices achieved significantly the highest values of banana production and sales. We conclude that improving information access through farmers’ preferred communication channels, having women-inclusive trainings, and a combination of cultural practices are effective ways for sustaining adoption of the control practices

Remarks By Nelson Rockefeller Vice President-Designate

Remarks of New York Governor Nelson Rockefeller in the Oval Office after President Gerald Ford announced that he was nominating Rockefeller to be the 41st Vice President of the United States. President Gerald Ford nominated Rockefeller pursuant to Section 2 of the Twenty-Fifth Amendment following Ford’s succession to the presidency upon President Richard Nixon’s resignation.https://ir.lawnet.fordham.edu/twentyfifth_amendment_watergate_era/1006/thumbnail.jp

The effect of 12C + 12C rate uncertainties on s-process yields

The slow neutron capture process in massive stars (the weak s-process) produces most of the s-only isotopes in the mass region 60 < A < 90. The nuclear reaction rates used in simulations of this process have a profound effect on the final s-process yields. We generated 1D stellar models of a 25 solar mass star varying the 12C + 12C rate by a factor of 10 and calculated full nucleosynthesis using the post-processing code PPN. Increasing or decreasing the rate by a factor of 10 affects the convective history and nucleosynthesis, and consequently the final yields.Comment: Conference proceedings for the Nuclear Physics in Astrophysics IV conference, 8-12 June 2009. 4 pages, 3 figures. Accepted for publication to the Journal of Physics: Conference Serie

Constraints on Type Ib/c and GRB Progenitors

Although there is strong support for the collapsar engine as the power source of long-duration gamma-ray bursts (GRBs), we still do not definitively know the progenitor of these explosions. Here we review the current set of progenitor scenarios for long-duration GRBs and the observational constraints on these scenarios. Examining these, we find that single-star models cannot be the only progenitor for long-duration GRBs. Several binary progenitors can match the solid observational constraints and also have the potential to match the trends we are currently seeing in the observations. Type Ib/c supernovae are also likely to be produced primarily in binaries; we discuss the relationship between the progenitors of these explosions and those of the long-duration GRBs.Comment: 36 pages, 6 figure